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Astron Astrophys. 1991;244:181-9.

H2CS abundances and ortho-to-para ratios in interstellar clouds.

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Department of Physics and Astronomy, University of Massachusetts, Amherst 01003, USA.
U MA, Amherst, Five Coll Radio Astronomy Observatory


Several H2CS ortho and para transitions have been observed toward interstellar molecular clouds, including cold, dark clouds and star-forming regions. We derive H2CS fractional abundances f(H2CS) approximately 1-2 10(-9) relative to molecular hydrogen towards TMC-1, Orion A, and NGC 7538, and approximately 5 10(-10) for L134N. The H2CS ortho-to-para ratios in TMC-1 are approximately 1.8 towards the cyanopolyyne peak and the ammonia peak, which may indicate the thermalization of H2CS on 10 K grains. We derive a ratio of approximately 3, the statistical value, for Orion (3N, 1E) and NGC 7538, while we find a value approximately 2 for Orion (KL).

[Indexed for MEDLINE]

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